<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
sadggs
<button onclick="open();">btn</button>
<script>
        document.execCommand('selectAll');
        document.execCommand('Bold', 'false', null);
    function open() {

    }
</script>

</body>
</html>